drive: Minor cleanup around ChangeListLoader::LoadFromServerIfNeeded()

chrome/browser/chromeos/drive/change_list_loader.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/drive/change_list_loader.h"
 
 #include <set>
 
 #include "base/callback.h"
 #include "base/metrics/histogram.h"
@@ skipping 628 matching lines @@
 
   // Sets the refreshing flag, so that the caller does not send refresh requests
   // in parallel (see DriveFileSystem::LoadFeedIfNeeded).
   //
   // The flag will be unset when loading completes.
   refreshing_ = true;
 
   resource_metadata_->GetLargestChangestamp(callback);
 }
 
+
+void ChangeListLoader::CheckForUpdates(const FileOperationCallback& callback) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK(!callback.is_null());
+
+  if (loaded() && !refreshing())
+    LoadFromServerIfNeeded(DirectoryFetchInfo(), callback);
+}
+
 void ChangeListLoader::UpdateFromFeed(
     scoped_ptr<google_apis::AboutResource> about_resource,
     ScopedVector<ChangeList> change_lists,
     bool is_delta_feed,
     const base::Closure& update_finished_callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!update_finished_callback.is_null());
   DVLOG(1) << "Updating directory with a feed";
 
   change_list_processor_.reset(new ChangeListProcessor(resource_metadata_));
@@ skipping 166 matching lines @@
     for (size_t i = 0; i < callbacks.size(); ++i) {
       base::MessageLoopProxy::current()->PostTask(
           FROM_HERE,
           base::Bind(callbacks[i], error));
     }
     pending_load_callback_.erase(it);
   }
 }
 
 }  // namespace drive